Apparatus for making valve sleeves

ABSTRACT

Apparatus for manufacturing a cylindrical sleeve for a hydraulic flow control valve, in which sleeve a plurality of longitudinally extending peripherally spaced grooves are provided in the bore, such that the grooves terminate axially internally of the sleeve and in such a manner that the sleeve is constructed in one piece.

United States Patent [191 Bishop [451 Oct. 16, 1973 [54] APPARATUS FOR MAKING VALVE 1,335,864 4/1920 Stevenson 90/8 EE E 3,079,732 3/1963 Rawstron et al...

2,923,209 2/ I960 Pelander 90/32 X [76] Inventor: Arthur E. Bishop, 5516 Westwood Ln., Birmingham, Mich. 21 Filed; Mar. 1 71 Primary ExaminerGil Weidenfeld Attorney-Hill, Sherman, Meroni, Gross & Simpson [21] Appl. No.: 124,902

Related U.S. Application Data [62] Division of Ser. No. 714,509, March 20, 1968, Pat.

No. 3,591,139. ABSTRACT [52] U.S. Cl 90/24 R, 90/38, 51/58 Apparatus for manufacturing a cylindrical sleeve for a [51] Int. Cl. S23d 5/00 hydraulic flow control valve, in which sleeve a plural- [58] Field of Search 90/24 R, 29, 31, ity of longitudinally extending peripherally spaced 90/32, 38, 56, 28.1, 8, l0, DIG. 8, 15.1 A; grooves are provided in the bore, such that the 51/58, 59 R, 59 SS, 57; 125/11 A; 29/558 grooves terminate axially internally of the sleeve and in such a manner that the sleeve is constructed in one [56] References Cited piece.

UNITED STATES PATENTS 3,466,975 9/1969 Feutrel et al. JO/28.1 4 Claims, 14 Drawing Figures m a a? X/ ,25

PAIENTEnnm s 1915 SHEEI 1 [IF 7 INVENTOR. 77/0? 5 5/5/701 #w 'TTORNEYS PATENTEDBBT 16 ms 3.765.305

SHEET so; 7

INVENTOR.

4k THU/Q 5 5 mm M W T YS PAIENIEUUBI 16 1973 3,765,305

INVENTOR.

WQk/M ATTORNEYS 1 APPARATUS FOR MAKING VALVE SLEEVES RELATED APPLICATIONS This application is a division of my parent application Ser. No. 714,509, filed Mar. 20, 1968 now US. Pat. No. 3,591,139.

BAcmrouss' or are memos" The invention Ki lithe emanates; v l'v's, are is, particularly related to such valves employed in twodirectional control systems such as power steering for automotive vehicles or the like. In recent years, fourlic fluid under the control of the grooves, depending upon the degree of relative oscillation between the "vaiveeareana"vawsleeve.'In the prior aminesleeves for such rotary valves have been peripherally annularly grooved on the outer surface to provide for porting of the hydraulic fluid and have been longitudinally or axially slotted on the internal: surface.

In order to provide for termination of the slots internally of the sleeve, opposite ends of the sleeve were provided with an undercut shoulder and a ring,

conventionally cadmium plated; was press-fitted into both ends of the sleeve, thereby providing termination of the slot. To applicant's knowledge, no

prior art valve sleeve has ever been constructed of a single piece as herein specified.

SUMMARY. OF THE INVENTION Three-piece valve sleeves have been manufactured in the millions over aperiod-of time. The steps of manufacture have become quite refined but are, nevertheless, extremely numerous and the valve is arelatively expensive item. Further, and stillmore important, the manufacture of three-piece valve'sleeves inherently incorporates several important deficiencies in the finished product. As such valve sleeves have been-manufactured in the prior art, press fits are employed to the two end rings. It is essential that such fits be tight but it will be appreciated'thatif the tolerance between the fitting parts is slightly too loose, theywill become disassembled in use, and, conversely, when the fit'is too tight, a warping ofthe. externalperiphry of the sleeve occurs. Any sticking of the valve component parts in such critical systems as automotive power steering,

provides an unacceptablesystem and-great care rnust' be exercisedinthe manufactured of three-piece sleeve In accordance with the present invention, an annular valve sleeve is provided with a plurality (conventionally six) of equally spaced longitudinal grooves on the internal bore surface thereof. These grooves are, in accordance with the present invention, scooped from the interior surface of the sleeve by means of a tool specifically controlled to move in an arcuate path, thereby providing a groove of maximum depth at the midpoint of its length and a gradually decreasing depth toward its opposite ends.

Whereas conventional prior practice has employed single-pass broaching as the technique of providing the longitudinally extending slots, the present invention contemplates machining the slots individually one at a time. Broaching provides, in practice, great difficulty in achieving concentricity of the broached grooves and lands relative to the outside surface of the sleeve. Accordingly, in the prior art, after broaching a plurality of longitudinally extending slots, the part must be recentered on its interior broached surface and remachined on its external surface. It will be appreciated that in steering valves, for example, the internal diameter of the sleeve must be true and accurate to within 0.0002 inches absolute parallelity and within 0.001 inches of run-out (0.0005 inches eccentricity). Utmost absolute accuracy is, accordingly, required and as those skilled in the art of machining are aware, such tolerances create extreme problems in the manufacture of the part.

In accordance with the present invention, the number of steps of machining are substantially reduced and are rendered less expensive. The steps comprise: (l) providinga blank annular sleeve; (2) accurately finishing the outside surface of the sleeve (for example by grinding); (3) colleting the part by the outside surface thereof); (4) cutting the grooves inside the sleeve (5) hardening the surfaces of the sleeve; (6) grinding the internal diameter of the sleeve colleted from the outside; and (7) polishing the outside and inside surfaces of the sleeve. It will be observed from the above list of manufacturing steps that substantially no retrueing of the parts is required and the cost of the manufacture is, accordingly, inherently low, assuming that the grooves can be cut inside the part. In accordance with the present invention, and through the use of the apparatus specifically hereinafter described, this may readily be accomplished.

In accordance with the invention, grooving apparatus is provided in which a single cutting tool is mounted upon the end of an oscillating finger. The finger is arcuately moved in a generally axial path within the sleeve at a high speed, the arcuate path adjustably intersecting the interior surface of the sleeve so that a shallow trough with an arcuately curved bottom surface is cut from the interior surface of the sleeve. In the apparatus preferably employed for the manufacture of the groove, the cutter moves in one direction in an interference path with the sleeve to remove metal therefrom and upon withdrawal is moved toward the axis of the sleeve bore and away from the interior surface of the sleeve to thereby prevent contact on the return stroke. Preferably, I employ a roughing cutter slightly smaller than the desired final slot width and a finish cutter having parallel sides and a width the same as the ultimately desired width of the slot. It has been found that slight relief at the sides of the cutting tool satisfactorily provides tool clearance. Movement of the cutter and workpiece to provide for depth adjustment of the groove during its cutting is accomplished by movement of the workpiece in a direction transverse to the direction of tool movement. A multiplicity of grooves may be provided by indexing the workpiece between the cutting of the grooves. To assure maximum accuracy, I prefer to rough and finish out the slots without rechucking the workpiece and, accordingly, a two-station apparatus is preferred. With such apparatus, the sleeve is chucked, rough slotted, moved to a second station, finish slotted and removed from the machine.

The result of the machining operations hereinabove described is the provision of a one-piece valve sleeve having extreme dimensional stability. No press fits are employed, no heating, spot-welding, or any other form of securing component parts to the sleeve is necessary. Since the individual slots are cut from the interior surface of the sleeve by a machine having a cutting stroke precisely oriented to the outside surface of the sleeve in its chucked or colleted condition, none of the tool deflection characteristics of multiple broaching are encountered and, accordingly, the slots are each cut to a depth precisely equal to each other relative to the outside surface and the slots are precisely equally spaced. Accordingly, finishing the inside bore diameter of the sleeve after the grooves are cut provides precisely accurate inside and outside cylindrical surfaces and valve ports. These surfaces are essentially completely accurate with respect to concentricity and, more particularly, the multiple valve grooves have precise concentricity relative to the axis of the sleeve. Described another way, a line drawn generally radially of the sleeve passing through the center of each of the slots will intersect the axis of the sleeve rather than intersecting each other at some point removed from the axis of the sleeve as often occurs when broaching is employed.

It is, accordingly, an object of the present invention to provide an improved, inexpensive, valve sleeve having extreme accuracy of dimension.

Still another object of the invention is to provide a novel apparatus for the manufacture of a one-piece valve sleeve having inwardly facing grooves terminating within the boundaries of the sleeve.

Still another object of the present invention is to provide an improved and greatly simplified method of manufacturing an annular valve sleeve having axial internally facing grooves therein.

Still another object of the present invention is to provide an improved and greatly simplified method of manufacturing an annular valve sleeve having axial internally facing grooves therein.

A further object is the provision of a valve having absolute rigidity and which is immune to failure distortion or leakage at high pressures.

Yet a further object of the invention is to provide a novel method of manufacturing an internally slotted valve sleeve.

Still other objects and features of the present invention will be apparent from the specification and drawings as hereinafter set forth:

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side-elevation in partial cross-section of a steering gear embodying a valve sleeve constructed in accordance with the prior art;

FIG. 2 is a cross-sectional view taken along the line II--Il of FIG. 1;

FIG. 3 is a cross-sectional view ofa valve sleeve configuration constructed in accordance with the present invention in the environment of the steering gear shown in FIG. 1;

FIG. 4 is a side-elevational view of an apparatus constructed in accordance with the principles of the present invention for the manufacture of an improved valve sleeve;

FIG. 5 is a plan view, in partial cross-section of the apparatus shown in FIG. 4;

FIG. 6 is a side-elevational view in cross-section taken along the line, generally, VI-VI of FIG. 5;

FIG. 7 is a side-elevational view in partial crosssection showing an enlargement of the automatic feed control shown in FIG. 4;

FIG. 8 is a cross-sectional view taken along the line VII-VII of FIG. 7;

FIG. 9 is a plan view in partial cross-section taken along the line IX-IX of FIG. 6;

FIG. 10 is a cross-sectional elevation of the chuck actuating yoke mechanism, taken along the line X-X of FIG. 6;

FIG. 11 is a cross-sectional view of the indexing mechanism taken along the line XIXI of FIG. 6;

FIG. 12 is a cross-sectional view of the workpiece feed control mechanism taken along the line XllXll of FIG. 5;

FIG. 13 is an enlarged cross-sectional view illustrating the movement of the tool relative to the sleeve workpiece; and

FIG. 14 is a diagrammatic illustration of the effective path of relative movement between the tool and the workpiece in manufacture of the valve sleeve of the present invention.

DETAILED DESCRIPTION Power steering systems have been manufactured and sold commericaly for many years. In recent times the valve ordinarily employed in such variable ratio systems has been a so-called rotary valve in which a centrally located valve core is oscillated relative to a valve sleeve to provide for the control function. Such valve systems have been shown and discussed in prior art references such as for example U.S. Pat. Nos. 3,162,263 and 3,273,465, to Arthur K. Brown, Jr., and Robert E. Eddy, respectively. Such a system is illustrated in FIGS. 1 and 2. There, a steering system of generally conventional nature is shown wherein a valve core 10 is connected to an hour glass steering worm 11 by way of a torsion bar 12. The worm ll drives the worm follower 13 by means of a cam track 14 so that rotation of the shaft 10 and worm 11 cause oscillation of the crossshaft 15 and its attached pitman arm 16, to provide steering movement of the dirigible wheels, not shown. A valve sleeve 17 co-operates with the valve core 10 to provide control of a pressurized hydraulic medium. In the conventional apparatus, the sleeve 17 is rigidly secured for rotation with the worm 1 1 by means ofa positioning aperture 18 and pin 19. A lost motion connection between the valve core 10 and the worm 11 is provided by means of a plurality of pins 20 co-operating with slots 21 such that an initial rotation of several degrees is permitted between core 10 and the worm 11 before the stop pins 20 provide a direct force transmission. As a result of this arrangement, slight relative oscillation of the valve core 10 and the sleeve 17 provide hydraulic power steering control but failure of the power steering system for any reason does not eliminate manual steering which may then be effected between the valve core 10, the pins 20, and the worm 11.

As above noted, the above described valve operation of a power steering system is well known in the art. Asmay be seen from a careful consideration of FIG. 1, the sleeve 17 is provided with a pair of annular rings 22 and 23 press-fitted into the ends of-respective counter bores 24, and which act to terminate the axial ends of slots 26,27. The slots 26,27 in the sleeve 17 provide control function for directing fluid under pressure from hydraulic pressure inlets 28, in the sleeve 17 to respective power steering cylinder inlets. 26 or 27 byway of distributing slots 30. Hydraulic fluid under pressure distributed from the slots is directed, depending upon the direction of relative rotation between the core 10 and the sleeve 17, alternatively to the power cylinder ports 26 or 27 and from thence torespective sump, or

pump inlet pressure slots 31 leading to the or sump outlet 32.

In past practice, the sleeve 17 has, asabove noted, been constructed of three unitized parts, namely, the sleeve proper l7 andthe endrings 22,23.,Thepressure present in the sleeve slots 26,27is, of course, operative against the rings 22,23'andit has been found inpractice that this multiple part sleeve structure has several imlow pressure portant deficiencies. In the first place, conventional manufacturing techniques employedtin the construction of the sleeve have required that the rings 22,23-be press-fitted into the sleeve. In ordinary manufacturing.

permit subsequent failure ofthe sleeve inoperation under high pressure. In such circumstances, it has been found that one or both of the rings may actually blow out of the ends of the sleeve. Alternatively, it has been found that as a result of the press fit-of the sleeves into the bore, a permanentdeformation of the sleeve sufficient to cause a tight fit:between the sleeve and the housing of the steering gear, as at may result. In over-all effect, accordingly, it is clear thatthe threepiecesleeve shown in FIG. land universally employed in modern power steering systems, has inherent defects of a substantial nature. Still further, however, the manufacture of the three-piece. sleeveis expensive.

As those skilled in the art of manufacturing'mechanical components are aware, the construction of a threepiece sleeve of the type shown at 17,22 and 23 requires the series of steps approximately two dozen in number when the sleeve is manufactured in accordance with prior art techniques. Conventionally, such a sleeve is manufactured with the use. of a a single multi-tool broach. Such a broach has six working portions which, when the broach is axially passed through the bore of the sleeve, simultaneously broaches out six slots comprising the three slots 26 and the three slots 27. This broaching technique would, at first glance, appear to be an extremely efficient and rapid method of manufacture. However, the related positioning and cutting steps require approximatey 24 actual single operations. These are, in their usual order of application, as folfinish bore and face the counterbores 24 and 25 accurately to the external ground surface; (8) turn the external O-ring grooves for O-ring seals 36; (9) drill radial holes; l0) carburize and harden, at least the surface of the part; l l clean; l2) hone or otherwise finish size the trim pin hole 19a; (l3) (l4) (l5) (l6) rough machine, grind, cadmium plate and externally grind ring 22; (I7 (l8) (19) (20) similarly machine ring 23; (21 and 22) press fit rings 22 and 23 in the counterbores 24 and 25; (23) finish grind the internal diameter of the assembled sleeve (24) finish grind the external surface of .the sleeve. It has been found in practice that substantially all of the above listed steps are necessary to provide a completely accurate threepiece sleeve assembly.

The approximately 24 steps necessary to the satisfactory manufacture of the three-piece sleeve of the prior art may be reduced to seven operations through the construction of the sleeve in a single piece in accordance with the present invention. These steps are briefly: (1 finish form and turn the outside diameter of the sleeve and drill the internal bore thereof, and cut off from the bar; (2 chuck the finished external surface of the sleeve in the apparatus of the present invention, and rough and finish shape six internal slots; (3,,) drill radial holes; (4 carburize and harden the surface, at least, of the sleeve; (5,) clean; (6,) internal grind the internal diameter of the sleeve; and (7,) hone the hole 19a.

A consideration of the difference in number of manufacturing steps and the type of steps shows that the method of the present invention eliminates a large number of steps incident to the manufacture and inser tionof the annular slot closing rings 22,23. However, just as important is the elimination ofa number of steps relating to assuring that the slots are properly centered relative to the sleeve. In the prior art manufacturing process the six slots were simultaneously broached so that each slot was properly oriented relative to the remaining slots. However, it is well known in the manufacturing industry that the broach has a tendency to move off center as it passes through the sleeve with the result that the finished broachedslots, while properly positioned relative to each other may well be eccentric of the center of the sleeve as determined by the center of the outside cylindrical surface thereof. Accordingly, finish machining of the outside surface has, in the past, been left until after finish machining of the interior surface so that the external surface can properly be rendered completely concentric with the broached slots. In accordance with the present invention, the external diameter of the sleeve is accurately finish machined before any other steps are undertaken and the slots are individually machined in the interior surface of the sleeve with positive reference to the external diameter. Further, no press-fitting of any sort is required and, accordingly, no re-surfacing of the external surface is necessary after press fitting operations, as in the prior art. It will be evident to those skilled in'the art that the substantial elimination of steps in the manufacturing process materially reduces the cost of the finished part.

It will be apparent to those skilled in the art that an important aspect of this improved method of manufacturing valve sleeves is the manufacture of the internal slots in a dead-end fashion. This is accomplished in accordance with the present invention on an apparatus designed to carve the slots generally arcuately from the interior cylindrical surface of the sleeve. Such a sleeve is shown in FIG. 3 where the slots 126 and 127, respectively, are cut in the internal surface of the sleeve 117. The sleeve 117 is completely interchangeable with sleeve 17 in terms of its ultimate function and operation. It is, however, substantially less expensive and less subject to failure.

The arcuate slots 126 and 127 may be fashioned in several ways. A very high speed, efficient and satisfactory method of manufacture is disclosed herein and provides a tool movable relative to the sleeve in an arcuate path. In the embodiment of the invention illustrated, the sleeve is accurately positioned in a chuck or collet by its external, previously finished, surface. The sleeve is then oscillated relative to the tool. While it is, of course, understood, that the tool may be moved through a complex motion relative to the workpiece to construct the slots, the apparatus herein illustrated provides for simple pivotal movement of the tool about a fixed axis in combination with a cam controlled oscillation of the workpiece in a direction generally transverse to the longitudinal axis of the workpiece. By simultaneously pivotally oscillating the tool and oscillating the workpiece a relative, progressive penetration of the workpiece by the tool is accomplished. The cutting action is shown diagrammatically in FIG. 14 where the relative movement of the tool and the workpiece are diagrammed. As can there be seen, the tool moves forward in the cutting stroke direction in arcuate sequentially deeper paths 40a, 40b, 400 relative to the workpiece and returns on a straight path 41 spaced inwardly of the internal surface of the sleeve.

Apparatus for effectively machining the sleeves is shown in FIGS. 4 through 12. As there shown, an oscillating sleeve holding support 50 is provided. The support 50 is provided with a transverse bore 51 supporting a sleeve 52 rotatable therein by way of bearings 53. Opposed collets 55 are provided having tapered chuck portions 55 for co-operation with the sleeve 117 by the external peripheral surface thereof. The wedge chucks 55 are axially slotted in the conventional manner and tightly engage the sleeves 117 upon axial movement of the collet actuating member 56 toward the pivot axis 60 of the support 50. Springs 57 acting against blocks 58 secured to the sleeves 56 normally cause the collets 55 to resiliently engage the workpiece or sleeve 117, while a disengaging yoke 61 pivots on an eccentric 62 co-operating with the sleeve 54 to move block 58 and actuator 56 in the chuck disengaging direction upon movement of the yoke rollers 63 radially outwardly relative to axis 60. The sleeve 54 is symmetrical about the axis of rotation 60 so that two workpieces are carried by the support 50. By providing a pair of work stations, rough machining may be accomplished at one work station with finish machining being accomplished at the second work station without necessitating removal of the sleeve from the machining apparatus between rough and finishing steps.

Movement of the support 50 from stage to stage is permitted by mounting the support 50 for rotation about the axis 60 in bearings 65,66. The shaft 67 is rigidly supported by a splined connection at 68 to the main outer housing of the apparatus 69. Shaft 67 carries a cam 70 shown in FIG. 9 which is arranged to provide radial outward movement of the co-operating yoke rollers 63 as the support 50 rotates between the finish cut position and the rough cut position, i.e., as the support 50 rotates in the clockwise direction as viewed in FIG. 9. Thus, after finish cutting the sleeve 117 indicated at the right-hand side of FIG. 6, and rough cutting the sleeve on the left-hand side of FIG. 6, the support 60 is bodily rotated at 90 at which time the sleeve 117 is released and removed and a new sleeve having the outside surface thereof finished but otherwise only rough machined, is inserted in the chuck 55 and the support 50 rotated another 90 to position the newly inserted sleeve in the rough cut position shown at the left in FIG. 6. At the same time, the previously finished rough cut sleeve 117 is moved through the idle position in which the chuck is not manipulated, to the finish cut position for finish cutting. It will be observed that the radius 70a clockwise of the cam 70 is constant from a point approximately indicated at 70b clockwise to approximately the point indicated at 700 so that slight oscillations of the support 50 relative to the cam 70, when in the rough-cuttinish-cut condition, will not effect disengagement of the chuck 55 of either sleeve 117.

The cutting tools 39 are held by two holders 72 by any conventional, adjustable, securing device 73 and are pivotal about the axis 74 by way of arbor shaft 75 supported in bearings 76,77. The tools 39 may be adjusted longitudinally of their length by the adjusting device 73 and may be adjusted transversely of their longitudinal axis by way of guides 78 in any convenient adjustable manner. The tool support shaft 75 is oscillated by means of crank arm 80 linked by way of links 81 to cam shaft 82 and eccentric 83 thereon. The cam shaft 82 is rotated by means of a flywheel pulley 84 driven by belts 85 from any conventional rotary power source. As the cam shaft 82 rotates, it simultaneously oscillates the cranks 80 and hence the support shafts 75 in first the clockwork and then the counterclockwise direction so that at any given instant, both the tools 39 are acting together in the work stroke or the return stroke. As viewed in FIG. 5, the work stroke is the clockwise direction of oscillation of the cranks 80, during which the tools 39 move into the interior of the sleeves 117.

The support 50 is held in the work machining positions by stop abutments 90. The support 50 is constantly biased in the clockwise direction as viewed in FIG. 5 so that the abutment is held tightly in engagement by pressure of approximately 400 pounds against stop support 91 which is oscillatably pivoted about its axis 92. As can be seen from FIG. 5, if the stop 91 is oscillated in a clockwise direction, the stop abutment 91 will move toward the left, causing the support 50 to oscillate slightly in a counterclockwise direction against a loading rod 94 which is moved upwardly as viewed in FIG. 5 by an air motor 95 or the like. The rod 94 is reciprocably carried by pivoted links 96 so that its end 98 seats in arcuate sockets 99 in a position controlling cam 100. The biasing rod 94 operates to provide for slight clockwise oscillations of the support 50 upon oscillation of the abutment stop 91 in a counterclockwise direction about its axis 92, for purposes described below. Further, the rod 94 operates, in combination with a reciprocating motor 101 and rack 102 to oscillate the support 50 through a 90 rotation simultaneously with delatching of the abutment 91 by reciprocal motor 103 at the completion of the machining process relative to a given sleeve. Downward movement of the rod 94 in response to reverse movement of motor 95 causes rack 102 to engage the co-operating gear 104 and subsequent left-hand movement of motor 101 causes clockwise rotation of gear 104 carrying with the supports 50.

The effective feeding of the tool 39 into the workpiece 117 is accomplished by changing the position of the workpiece 117 rather than by modifying the adjusted position of the tool 39. This can be understood from a consideration of FIG. 5. Withthe position of the parts as there shown, if the workpiece holder 50 were rigidly maintained in the position illustrated, and the tools 39 were oscillated in a clockwise direction about their pivot axes 74, the respective tools 39 would cut a maximum cut into the interior surface of the respective workpieces 117. In other words, in the position shown, the workpieces 117 and the tools 39 are in their relative position of finishing the internal slot. Immediately upon indexing the workpiece in the machine, the parts assume the position shown in FIG. 5. Accordingly, in order to permit a cutting depth of approximately 0.002 of an inch for the first stroke rather than the full depth of approximately 0.080 of an inch, it is essential that the workpieces 117 be oscillated in a clockwise direction about the central axis 60 moving them transversely away from the pivot, axes 74 of the tools 39. This is accomplished by means of a cam 110.

which acts against cam follower 111 connected to the abutment stop 91. As the earn 110 rotates in a counterclockwise direction as viewed in FIG. 5, the surface 110a permits the cam follower 1 11 to move radially toward the axis of rotation of the cam 110 under the influence exerted by motor 94 permitting the workpiece holder 50 to oscillate in the clockwise direction. At the same time, oscillation of the tools 39 will cause a com bination relative movement along the line 40a shown at FIG. 14 taking a short 0.002 of an inch deep cut from the central portion internal surface of the sleeve. Continued rotation of the cam 110 causes surface 110b, or the return stroke surface thereof, to come in contact with the follower 111 causing the workpiece holder 50 to be moved slightly further in a clockwise direction away from the effective movement of the tool 39 along the path 41.

The cutting feed for the tools 39 is provided by reciprocating cam 110 upwardly as viewed in FIG. 6 and toward the observer as viewed in FIG. 5. This is accomplished by upward reciprocation of rod 120 which is rotatably carried relative to the gear 121 by means of 'a bearing 122 and is biased downwardly by spring 123 secured to a housing 69. Gear 125 is rotated by the cam shaft 82 carrying mating gear 126. The gear 125 is slid upwardly upon upward movement-of shaft 120 and, as can be seen from FIG. 6, such upward movement will cause movement of the cam follower 111 outwardly to a greater extent as the surface 110a increases in radius. The shaft 120 is preferably moved upwardly at a rate provided approximately 0.010 of an inch increased radius of cam 110a under the follower 111 with each rotation of the cam 110 (providing, in turn, 0.002 inch increase in depth of cut) thereby requiring 40 revolutions of the cam 110, or 40 oscillations of the workpiece support 50 and tools 39 to accomplish a full depth slot cut of 0.080 inches. It will be observed that the return stroke portion 11% of cam is of constant configuration, with the result that the return path 41 shown in FIG. 14 is constant throughout the machining operation.

Upward reciprocation of the shaft is automatically accomplished by means of a separate power source indicated at which rotates a feed shaft 131 by way of a gear reduction transmission 132 of any conventional form. Preferably, the transmission 132 is provided with a plurality of gear reduction ratios so that the feed shaft 131 may be rotated at different adjusted speeds. The shaft 131 carries cam 133 secured thereto for rotation in the counterclockwise direction as viewed in FIG. 8. Thus, as shaft 131 rotates, cam 133 lifts cam follower 134 upwardly pulling shaft 120 therewith. If the shaft 131 is rotated at a speed faster than above described, more than 0.002 inches per cut will be achieved and, accordingly, fewer cuts per slot will be employed. Similarly, a reduction in speed in the shaft 131 would provide a smaller depth of cut per work stroke of the tool 39 and, hence, require more strokes per finished slot.

Since the machine of the present invention cuts one slot at a time, for each workpiece, it is desired that the workpiece be indexed at the completion of each slot to thereby provide for machining of the remaining five slots of the valve sleeve. This is automatically accomplished by means of cam 135 likewise secured to shaft 131 for rotation thereby. With each complete rotation of shaft 131, and hence with each completion of a slot, shaft 136 oscillates in a clockwise direction as viewed in FIG. 6 forcing shaft 138 downwardly. The downward movement of shaft 138 cuases pivotal movement of detent dog 139 by way of plunger 140 and abutment 141 to lift the detent 142 upwardly against spring 143 freeing sleeve 52 for rotation in the counterclockwise direction as viewed in FIG. 11 under the influence of indexing dog 139 pivotally carried by shaft 138 at pin 144. Upward movement of the shaft 138 after the indexing operation carries the pivotal dog 139 upwardly in the dotted line condition shown at 139a in FIG. 11.

A counter of any conventional mechanical sort may be applied to the shaft 52 or the shaft 131 to count the number of complete slotting operations performed by the apparatus and to automatically energize motors 95,101 and 103 to index the work support to move the rough cut valve sleeve into the finish cut position and to move a new, uncut sleeve into the rough cut position, as above described.

The machine, as above described, provides an effective apparatus for the internal slotting of a valve sleeve or the like with a plurality of longitudinally extending slots. The slots constructed are dead-end in the sense that they do not reach the axial ends of the valve sleeve and, at the same time, they are highly accurate and all of the slots are properly concentric with respect to the finished outside diameter of the workpiece and with respect to each other. It will be observed that the tool 39 moves in a manner relative to the slot such that its leading edge 39a maintains a substantially constant cutting angle relative to the bottom of the slot. Accordingly, the side rake of the tool 39 is maintained substantially constant throughout its stroke and carbide cutting tools are readily used without danger of breakage due to variations in tool angle. It will be appreciated, however, that, as above noted, the cutting movement of the tool 39 may also be modified by moving the tool along the tool support guides 78 automatically during the cutting operation rather than modification of the position of the workpiece by oscillation of the work holder 50. Similarly, a small grinding head or spark gap metal eroder could be carried by the tool holder 72 to grind the slots. All of such tools will, however, travel substantially the same type of interference path with the workpiece as above described. It will be appreciated, of course, that the tool 139 could be reciprocated in a straight line internally of the sleeve and moved transversely to its direction of reciprocation to cut the internal slot. Utilization of conventional tools is difficult with recriprocal action, however, in view of the change of cutting tool clearance angles necessitated by the generally arcuate bottom configuration of the slot and, accordingly, the apparatus specifically illustrated is preferred.

The sleeve constructed in accordance with the present invention is substantially superior to prior art threepiece sleeves. It is incapable of failure as a result of the application of slot end rings and concentricity of the component parts of the sleeve is absolutely assured. Since steering is such an important aspect of vehicle safety, the elimination of valve failures as well as a substantial reduction in over-all manufacturing costs, provides an important contribution in vehicle construction.

I claim:

1. Apparatus for manufacturing a valve sleeve having a cylindrical bore, comprising chuck means holding the sleeve fixedly by its external surface, a tool having a work eroding portion, support means for said tool for movement of said portion into interference relation with the internal surface of said bore of said sleeve, means reciprocating said support means to move said tool eroding portion is moved through an arcuate interference path with the internal surface of said bore through an area in the axial direction of said sleeve term'inating axially inwardly of the ends of the sleeve wherein a dead end groove is constructed in said sleeve.

2. The apparatus set forth in claim 1 including means increasingly adjusting the relative position of the tool and the sleeve to increase the depth of tool penetration to a final penetration equal to the finish groove depth.

3. The apparatus set forth in claim 2 including means indexing said sleeve to align said sleeve and tool for the formation of additional grooves sequentially upon completion of a precedng finish penetration.

4. The apparatus constructed in accordance with claim 1 which includes means to oscillate said sleeve transversely of its axis simultaneously with movement of said tool to move said tool into an interference condition with the inside surface of said sleeve during the forward working stroke of said tool and out of interference condition with said interior surface during return stroke thereof. 

1. Apparatus for manufacturing a valve sleeve having a cylindrical bore, comprising chuck means holding the sleeve fixedly by its external surface, a tool having a work eroding portion, support means for said tool for movement of said portion into interference relation with the internal surface of said bore of said sleeve, means reciprocating said support means to move said tool eroding portion is moved through an arcuate interference path with the internal surface of said bore through an area in the axial direction of said sleeve terminating axially inwardly of the ends of the sleeve wherein a dead end groove is constructed in said sleeve.
 2. The apparatus set forth in claim 1 including means increasingly adjusting the relative position of the tool and the sleeve to increase the depth of tool penetration to a final penetration equal to the finish groove depth.
 3. The apparatus set forth in claim 2 including means indexing said sleeve to align said sleeve and tool for the formation of additional grooves sequentially upon completion of a preceding finish penetration.
 4. The apparatus constructed in accordance with claim 1 which includes means to oscillate said sleeve transversely of its axis simultaneously with movement of said tool to move said tool into an interference condition with the inside surface of said sleeve during the forward working stroke of said tool and out of interference condition with said interior surface during return stroke thereof. 